Interlocked explosionproof switch housing and plug receptacle



Sept. 24, 1935. c. H. BISSELL 2,015,543

INTERLOCKED EXPLOSIONPROOF SWITCH HOUSING AND PLUG RECEPTACLE Filed July21, 1933 Patented Sept. 24, 1935 UNITED STATES PATENT OFFICE INTERLOCKEDEXPLOSIONPROOF SWITCH HOUSING AND PLUG RECEPTACLE poration of New YorkApplication July 21, 1933, Serial No. 681,547

3 Claims.

This invention relates to an explosion proof switch housing providedwith a plug receptacle with means for preventing operation of the switchwhen the plug is withdrawn from the receptacle, and means for preventingwithdrawal of the plug from the receptacle after the switch has beenactuated to the on position.

The invention consists in the novel features and in the combinations andconstructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanyingdrawing in which like characters designate corresponding parts in allthe views.

Figure 1 is a lengthwise, sectional view of the explosion proof switchhousing, parts in elevation, and the plug withdrawn from the receptacle.

Figure 2 is an end elevation of the switch housing cover and part of theswitch operating mechanism.

Figure 3 is an end elevation of the receptacle housing, partly insection.

Figures 4 and 5 are partial sectional views, similar to Figure 1,showing the position of the locking mechanism when the plug is insertedin the receptacle, and the switch operating mechanism is in the off andon positions respectively.

Explosion proof fittings are designed particularly for use in hazardouslocations. That is, where, on account of the surrounding atmospherecontaining inflammable gases, a spark from an electrical apparatus wouldbe likely to cause an explosion. As a caution against such explosions,explosion proof fittings are so constructed that the contact mechanismof the fitting is enclosed in a tight housing which is of such structurethat should any gases explode within the housing they will be cooledbelow the ignition point before reaching the outer atmosphere.Obviously, in the use of plug and receptacles, it becomes necessary toprovide some means whereby the circuit will not be closed, or opened, bythe separation of the plug and receptacle contacts.

This invention comprises generally, the combination of an explosionproof switch housing and a receptacle housing, a receptacle mounted inthe receptacle housing and connected to and controlled by the switch inthe switch housing, the switch housing being provided with switchoperating mechanism to shift the switch into on and. off positions, andmeans coacting with the plug and the switch operating mechanism andbeing operable upon withdrawal of the plug from the receptacle topreventoperation of the switch operating mechanism, and to prevent withdrawalof the plug after the switch operating mechanism has been shifted to onposition.

Referring to the drawing, Ill designates the explosion proof switchhousing which may be of any suitable form. As here shown, it comprises 5a rectangular box with base H, and end wall l2 perpendicular to the baseand provided with a threaded opening l3 to receive the conduit carryingthe electrical circuits. The opposite end projects outwardly from themain portion of the 1g housing at a substantial angle to the base H. Theside opposite the base I l is open, and is provided with a cover or capI 4, and is secured to the housing l2 by a plurality of screws 15. Thecoacting marginal faces of the housing and the cap 35 M are generallyground to a true accurate surface.

The angular end portion IB is provided with a receptacle housing l8which is secured to the end portion 15 in a manner similar to theattach- 20 ment of the cap I4 to the housing, namely by screws extendingthrough the holes l9 and threading into bosses formed in the angular endportion [6.

A plug receptacle 20 is secured to a plate 2| 25 which is clampedbetween the receptacle housing 18 and the end portion l6 of the switchhousing. These coacting surfaces are also ground true so as to limitthe. escape of any gases ignited within the switch housing. Thereceptacle 20 is pro- 30 vided with a plurality of terminals or contacts22 which are in turn electrically connected to and controlled by aswitch 23 by means of the wires or conductors 24. The switch 23 issecured in the housing [2 in any suitable manner. As 35 here shown, theswitch 23 is secured to a plate 23 which extends across the open side ofthe housing, and its ends are secured in recesses 25 by screws, or otherfastening means.

After the receptacle housing 58 has been se- 40 cured to the end !6 ofthe switch housing, and the receptacle 253 and plate 2| secured inplace, the end it of the switch housing is filled with a suitablesealing compound, as indicated in Figure 1 of the drawing. Thisestablishes a tight joint be- 45 tween the receptacle 29 and the conduitline entering the switch housing through the passage 23. The switch 23is provided with an operating member 26 which is pivotally mounted inthe switch proper and shiftable crosswise of the hous- 50 ing to operatethe switch into on and off positions.

The switch housing is provided with switch operating mechanism operablefrom the outside of the housing. This mechanism comprises a shaft 55 30journalled in a boss 3| formed in the upper portion of the cover I4. Tothe inner end of the shaft 33 is secured a yoke member 32, the fingersof which cooperate with the switch operating element 26 in such a mannerthat upon rocking the shaft 30, the element 26 is actuated to shift theswitch into its on or off position. The outer end of the shaft 30 isprovided with an operating manual 33 having a hub 34. The hub 34 isprovided with a slot or recess 35 extending perpendicular to the axis ofthe shaft 30 and so formed relative to the yoke 32 that it assumes aperpendicular position when the switch is actuated to the off position.

The receptacle housing I8 is provided with an arcuate portion 36 whichterminates in a plane parallel with the face of the hub 34, and isformed with a passage or chamber 38. A look member 40 is pivoted in thechamber 38 upon the shaft 4| which extends crosswise thereof. A coiledspring 42 surrounds the shaft 4| and has one end connected to the member40, and the other end to the portion 36, and normally rotates the member40 clockwise in the position shown in Figure l.

The lock member 40 is so arranged relative to the shaft 30 that itrotates in a plane perpendicular to the axis of the shaft 30, or so thatthe inner end travels, upon rotation, through the slot 35 formed in thehub of the manual 33. The bottom of the slot 35 is formed arcuate andconcentric with the axis of the shaft or pin 4|. The inner end of themember 40 is generally arcuate in shape, being truncated, or flattenedoif, as at 46 so when it assumes the position shown in Figures 4 and 5,the end 44 does not extend into the slot 35. It will be observed thatnormally the shaft 30 can not be rotated to actuate the switch into theon position due to the engagement of the locking member 40 with the hub34 of the manual.

50 designates generally, the plug which is formed with a cast body 5|,and a suitable cable clamp 52, a shell 53 in which is secured a terminalblock 54 provided with a plurality of terminals 55 complemental to theterminals 22 of the receptacle 20. The plug thus described forms per seno part of this invention, and may be of any suitable design orconstruction.

The shell 53 is provided with a boss 51, and the receptacle housing I8is provided with a groove 58. The boss 51 and the groove 58 aline theplug with the receptacle so that the proper contacts 55 will coact withthe terminals 22. The inner end of the shell 53 is provided with a.notch 60 and with a slot 6| in axial alinement with the notch 60, and soarranged relative to the boss 51 when the plug is inserted into thereceptacle housing the notch and slot cooperate with the outer end ofthe lock member 40 which is notched, or bifurcated at 62 formingprojections 63, 64.

When the plug is inserted into the receptacle housing and the contacts55 engage the terminals 22, the partition engages the projection 63 ofthe member 40 rotating the member in a counterclockwise direction,atwhich time the projection 64 of the member 40 extends into the slot 6|as shown in Figures 4 and 5. In this position, the inner end 44 of themember 40 has traveled out of the slot 35 whereupon the manual 33 may beactuated to shift the switch 23 into the on position. The actuation ofthe manual 33 in the counter-clockwise direction, Figure 2, to shift theswitch into on position, shifts the slot 35 out of alinement' with thefiat surface 46 of the end 44 of the lock member 40, as indicated inFigure 5. If an attempt is now made to withdraw the plug from thereceptacle, the partition 65 coacts with the projection 64 of the lockmember and tends to rotate the lock member in a clockwise direction,Figures 1, 4, and 5. However, due to the fact that the slot 35 is nowout of alinement with the surface 43 of the member 40, Figure 5, therotary movement of the latter will be prevented and it is impossible towithdraw the plug.

By the mechanism above described, I have provided a simple, durablelocking mechanism for the combination explosion proof switch housing andplug receptacle which is impossible to get out of order, and foohproof.It will be observed that should the cover l4 be removed from the switchhousing and replaced with the manual 33 actuated in the on position, thedevice could not be used due to the fact that it would be impossible toinsert the plug into the receptacle. In such instance, the portion orpartition 65 would engage the projection 64 of the lock member 40, andthe plug could not be inserted into the receptacle until the operatingmechanism had been properly alined.

What I claim is:

l. The combination of an explosion proof switch housing provided with adetachable receptacle housing, a receptacle mounted in said receptaclehousing and a plug slidable axially into and out of said receptaclehousing into and out of engagement with said receptacle, a switchmounted in the switch housing, a cover detachably secured to the switchhousing, a switch actuating member journalled in the cover and havingone end extending outwardly through the cover toward the receptaclehousing, and being operable to actuate the switch to on and offpositions, the receptacle housing being provided with an extension onone side, a latch member rotatably mounted in said extension on an axisextending transversely of the plug and receptacle, one end of said latchmember extending into the receptacle housing and being engageable by theplug when inserted in the housing, the outer end of said latch membercooperating with the outer end of the switch actuating member to preventactuation of the same after the plug has been Withdrawn from thereceptacle, and to prevent withdrawal of the plug from the receptacleafter the switch actuating mechanism has been actuated into on position.

2. The combination of a switch housing provided with a receptaclehousing, a receptacle mounted in the receptacle housing, and a plugslidable into and out of the receptacle housing into and out ofengagement with the receptacle,

a switch mounted in the switch housing, a cover detachably secured tothe switch housing, a switch actuating member rotatably mounted in thecover and having one end extending outwardly therefrom, the receptaclehousing being formed with an arcuate extension abutting the outward endof the switch actuating member, a latch member rotatably mounted in saidextension on an axis extending transversely of the plug and receptacleand having one end extending into the receptacle housing and beingengageable by the plug, the other end of said latch cooperating with theoutward end of the switch actuating mechanism to prevent rotation of thesame after the plug has been withdrawn from the receptacle, and toprevent withdrawal of the plug from the receptacle after the actuatingmember has been rotated into on position.

3. The combination of a switch housing provided with a receptaclehousing, a receptacle mounted in the receptacle housing, a plug slidableinto and out of said housing into and out of engagement with thereceptacle, a. switch mounted in the switch housing, a cover detachablysecured to the switch housing, a. rock shaft journalled in said coverand having its inner end coacting with the switch to operate the sameinto on and off positions, and its outer end extending toward thereceptacle housing, the receptacle housing being provided with anarcuate portion extending toward the outer end of the rock shaft andhousing the same, a latch member rotatably mounted in said projectionupon an axis transverse to the plug and receptacle having its inner endextending into the receptacle housing and being engageable by the plugwhen the same is inserted in the housing, the outer end of the rockshaft being provided with a slot, and the outer end of the latch memberbeing arranged to move into and out of said slot upon rotation about itsaxis, the latch member cooperating With the rock shaft to preventrocking movement thereof after the plug has been withdrawn from thereceptacle, and to prevent withdrawal of the plug after the rock shafthas been rocked to actuate the switch in on position.

CARL H. BISSELL.

